Living specimen induction chamber

ABSTRACT

The invention described herein provides an induction chamber used to sedate one or more living specimens. The induction chamber comprises at least one gas inlet through which anesthesia gas and oxygen are supplied. To minimize escape of anesthetizing gas is into the ambient room or surroundings, the induction chamber includes a gas outlet or port that draws anesthesia gas. A negative or vacuum pressure is applied to the gas outlet. The negative pressure draws gases from within the induction chamber, and may draw gases from the ambient surroundings around the induction chamber when a door allowing a lab technician access to the induction chamber interior opens. The induction chamber also comprises a device that obstructs gas flow through the gas outlet based on the position of the door. In one chamber design, when the door closes, the gas outlet is blocked. Thus, opening the door to the induction chamber causes anesthesia gas is to be drawn through the outlet while closing the door allows anesthesia gas to collect in the chamber and sedate any specimens located therein. The induction chamber is particularly useful for sedating a living specimen prior to insertion in an imaging box or chamber.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority under 35 U.S.C. §119(e) fromco-pending U.S. Provisional Patent Application No. 60/385,397 filed onMay 31, 2002, which is herein incorporated by reference for allpurposes; this application is also a continuation-in-part of U.S. patentapplication entitled “Multiple Output Anesthesia System” by RichardGeorge Dalgetty et al., filed on Feb. 20, 2002 (U.S. application Ser.No. 10/081,040), which is herein incorporated by reference herein forall purposes.

FIELD OF THE INVENTION

[0002] The present invention relates generally to anesthesia deliverysystems and imaging systems. In particular, the present inventionrelates to induction chambers used to anesthetize mammalian specimens inimaging and research applications.

BACKGROUND OF THE INVENTION

[0003] One new and specialized type of imaging involves the capture oflow intensity light—often on the order of only tens to hundreds ofphotons—from a light-emitting sample. The low intensity light source maybe emitted from any of a variety of light-emitting sources within aliving specimen, e.g., luciferase expressing cells within a mouse. Thesource of the light indicates portions of the sample, such as tracedmolecules in a particular portion of a mammalian specimen, where anactivity of interest may be taking place. Some specialized in-vivoimaging applications include analysis of one or more representations ofemissions from internal portions of a specimen superimposed on aphotographic representation of the specimen. The photographicrepresentation provides the user with a pictorial reference of thespecimen. The luminescence representation indicates portions of thespecimen where an activity of interest may be taking place.

[0004] Obtaining a luminescence representation often involves imagecapture over an extended period of time, e.g., minutes, in a specializedimaging box. The imaging box is a custom-made apparatus designed totightly control the amount of light in the box and minimize lightentering from the surrounding room. The living specimen is typicallyanesthetized during imaging to prevent movement that may affectprolonged image capture.

[0005] An induction chamber is typically used to anesthetize the livingspecimen before being placed in the imaging box. A laboratory technicianor researcher places one or more conscious living specimens in theinduction chamber. A combination of anesthetizing gas and oxygen is thensupplied to the induction chamber. The specimen remains in the inductionchamber until it loses consciousness, or is similarly sedated, and isthen transported by the laboratory technician into the imaging box.Transporting living specimens in and out of the induction chamber mayallow the anesthesia gas to escape into the ambient surroundings.Preferably, the amount of anesthesia gas that escapes is minimized.

[0006] Conventional induction chambers rely on a purge system to manageanesthesia gas escape. The purge system forces high-pressure oxygen intothe induction chamber before the door or user access is opened. Apassive exhaust port leading from the induction chamber interiorreceives the high-pressure purge oxygen and any gases present in theinduction chamber before the purge. One problem with purge systems isthat the high burst of oxygen, and/or removal of all anesthetizing gas,frequently awakens any living specimens in the induction chamber. When asingle living specimen is in the induction chamber, this is clearlydefeating to the intended induction chamber purpose. Lab technicianshowever often work with multiple living specimens at a single time andpurging the induction chamber to remove one specimen may then lead tomore than one specimen awakening.

[0007] In view of the foregoing, an improved induction chamber capableof anesthetizing one or more living specimens would be desirable.

SUMMARY OF THE INVENTION

[0008] The present invention relates to an induction chamber used tosedate one or more living specimens. The induction chamber comprises atleast one gas inlet through which anesthesia gas and oxygen aresupplied. To minimize escape of anesthetizing gas is into the ambientroom or surroundings, the induction chamber includes a gas outlet orport that draws anesthesia gas. A negative or vacuum pressure is appliedto the gas outlet. The negative pressure draws gases from within theinduction chamber, and may draw gases from the ambient surroundingsaround the induction chamber when a door allowing a lab technicianaccess to the induction chamber interior opens. The induction chamberalso comprises a device that obstructs gas flow through the gas outletbased on the position of the door. In one embodiment, when the doorcloses, the gas outlet is blocked. Thus, opening the door to theinduction chamber causes anesthesia gas is to be drawn through theoutlet while closing the door allows anesthesia gas to collect in thechamber and sedate any specimens located therein. The induction chamberis particularly useful for sedating a living specimen prior to insertionin an imaging box or chamber.

[0009] In one embodiment, the gas outlet is near the door. In a specificembodiment where the door is on the top portion of the chamber, the gasoutlet is vertically disposed on the top half of the induction chamber.In this case, suction of anesthesia gas removes a top layer ofanesthesia gas from a top portion of the induction chamber interiorcavity. One or more living specimens resting on the bottom half of theinduction chamber interior cavity are thus still exposed to anesthesiagas while the door is open. This allows the lab technician to remove oneor more specimens without awakening the other living specimens.

[0010] In one aspect, the present invention relates to an inductionchamber for delivering anesthesia gas to a living specimen. Theinduction chamber comprises a set of walls defining an interior cavity.The induction chamber also comprises a door that is movable between anopened condition that enables gaseous communication between the interiorcavity and the environment exterior to the induction chamber through anopening, and a closed condition that seals the interior cavity from theenvironment exterior to the induction chamber. The induction chamberfurther comprises a gas inlet disposed in one of the set of walls andcapable of providing anesthesia gas to the interior cavity. Theinduction chamber additionally comprises a gas outlet disposed in one ofthe set of walls and capable of drawing anesthesia gas from the interiorcavity when the door is in the opened condition. The induction chamberalso comprises a gas outlet obstruction that varies flow of anesthesiagas from the interior cavity through the gas outlet based on theposition of the door.

[0011] In another aspect, the present invention relates to a method ofusing an induction chamber. The induction chamber comprises a set ofwalls that define an interior cavity. The induction chamber alsocomprises a door that is movable between an opened condition and aclosed condition. The method comprises supplying an anesthesia gas intothe interior cavity. The method also comprises drawing anesthesia gasthrough a gas outlet disposed on one of the set of walls when the dooris in the opened condition. The method further comprises obstructing gasflow through the gas outlet when the door is in the closed condition.

[0012] In yet another aspect, the present invention relates to animaging system for capturing an image of a living specimen with acamera. The system comprises an imaging box having a set of wallsenclosing an interior cavity and a camera mount configured to positionthe camera to view the living specimen in the interior cavity while theliving specimen is anesthetized. The system comprises an inductionchamber. The induction chamber comprises a set of walls defining aninterior cavity. The induction chamber also comprises a door that ismovable between an opened condition that enables gaseous communicationbetween the interior cavity and the environment exterior to theinduction chamber through an opening, and a closed condition that sealsthe interior cavity from the environment exterior to the inductionchamber. The induction chamber further comprises a gas inlet disposed inone of the set of walls and capable of providing anesthesia gas to theinterior cavity. The induction chamber additionally comprises a gasoutlet disposed in one of the set of walls and capable of drawinganesthesia gas from the interior cavity when the door is in the openedcondition. The induction chamber also comprises a gas outlet obstructionthat varies flow of anesthesia gas from the interior cavity through thegas outlet based on the position of the door.

[0013] These and other features of the present invention will bedescribed in more detail below in the detailed description of theinvention and in conjunction with the following figures.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The present invention is illustrated by way of example, and notby way of limitation, in the figures of the accompanying drawings and inwhich like reference numerals refer to similar elements and in which:

[0015]FIG. 1 is a perspective view of an imaging system in accordancewith one embodiment of the present invention.

[0016]FIG. 2A illustrates a top prospective view of the front of theinduction chamber of FIG. 1 in accordance with one embodiment of thepresent invention.

[0017]FIG. 2B illustrates a top prospective view of the back ofinduction chamber of FIG. 1.

[0018]FIG. 2C illustrates a top prospective view of the door undersidefor the induction chamber of FIG. 1.

[0019]FIG. 2D illustrates a side cross sectional view of inductionchamber of FIG. 1 taken through the lateral midpoint.

[0020]FIG. 3 illustrates a process flow for using the induction chamberof FIG. 1 in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] In the following detailed description of the present invention,numerous specific embodiments are set forth in order to provide athorough understanding of the invention. However, as will be apparent tothose skilled in the art, the present invention may be practiced withoutthese specific details or by using alternate elements or processes. Inother instances well known processes, components, and designs have notbeen described in detail so as not to unnecessarily obscure aspects ofthe present invention.

[0022] I. Imaging System

[0023] In one aspect, the present invention relates to imaging systemsfor capturing an image of a low intensity light source. FIG. 1illustrates an imaging system 10 configured to capture photographic andluminescence images in accordance with one embodiment of the presentinvention. Imaging system 10 may be used for imaging a low intensitylight source, such as luminescence from luciferase-expressing cells,fluorescence from fluorescing molecules, and the like. The low intensitylight source may be emitted from any of a variety of light-emittingsamples which may include, for example, animals containinglight-emitting molecules, e.g., various mammalian subjects such as micecontaining luciferase expressing cells.

[0024] Imaging system 10 comprises an imaging box 12 having a door andwalls that define an interior cavity that is adapted to receive alight-emitting sample in which low intensity light, e.g.,luciferase-based luminescence, is to be detected. Imaging box 12 isoften referred to as “light-tight”, e.g., it seals out essentially allof the external light from the ambient room from entering the box 12,and may include one or more seals that prevent light passage into thebox when the door is closed. The seals may also be effective to preventanesthesia gases used within box 12 from escaping into the ambient room.Imaging box 12 is suitable for imaging including the capture of lowintensity light on the order of individual photons, for example.

[0025] Imaging box 12 includes an upper housing 16 adapted to receive acamera. A high sensitivity camera 20, e.g., an intensified or acharge-coupled device (CCD) camera, is mounted on top of upper housing16 and positioned above imaging box 12. CCD camera 20 is capable ofcapturing luminescent and photographic (i.e., reflection based images)images of a sample placed within imaging box 12. CCD camera 20 is cooledby a suitable source such as a refrigeration device 22 that cycles acryogenic fluid through the CCD camera via conduits 24. A suitablerefrigeration device is the “CRYOTIGER” compressor, which can beobtained from IGC-APD Cryogenics Inc., Allentown, Pa. Other methods,such as liquid nitrogen, may be used to cool CCD camera 20.

[0026] Imaging system 10 also includes an anesthesia delivery systemthat delivers anesthesia gas and oxygen. The anesthesia delivery systemincludes console 52, induction chamber 54 (FIGS. 2A-2D), and a gasdelivery device 56. Console 52 allows a user or lab technician tocontrol flow of anesthesia gas and oxygen from one or more gas outletson the console. The output of console 52 is a combination oflow-pressure oxygen and anesthesia gas. As shown, console 52 includestwo gas delivery outlets: a first gas delivery outlet for servicing gasdelivery device 56 and a second delivery outlet 71 that servicesinduction chamber 54.

[0027] Oxygen delivery conduit 58, such as a rubber tube or hose, isoperably coupled to an oxygen inlet of main console 52 and an outlet ofan oxygen supply source. For example, the oxygen supply source may be ahigh pressure oxygen cylinder or conventional medium pressure walloutlet. Conduit 60 is coupled to an outlet of main console 52 andcoupled to inlet of induction chamber 54 and allows gaseouscommunication between induction chamber 54 and console 52.

[0028] Induction chamber 54 receives oxygen and anesthesia gas fromconduit 60. Induction chamber 54 allows a user to anesthetize one ormore living specimens that fit within induction chamber 54, and will bedescribed in further detail with respect to FIGS. 2A-D. A passive gasoutlet is included in a side wall of induction chamber 54 and coupled toconduit 77. The passive gas outlet and conduit 77 allow gases to flowpassively from induction chamber 54. The gases in conduit 77 areprovided to filter 78. In one embodiment, the anesthesia gas isisoflurane and filter 78 is a charcoal filter that removes unusedisoflurane that passes therethrough. A filter model number 80120 F/AirCannister as provided by A. M. Bickford of Wales Center, N.Y. issuitable for use as filter 78. Filter 78 outputs primarily oxygen. Asshown, filter 78 outputs oxygen into the ambient room.

[0029] An active gas outlet is also included in a top portion of a sidewall of induction chamber 54 and is coupled to conduit 79. The activegas outlet and conduit 79 actively draws gases from induction chamber 54and provides them to filter 81. A pump 83 provides a negative pressureto the active gas outlet and conduit 79 the draws oxygen and anesthesiagas from the interior of induction chamber 54. The active gas outletwill be described in further detail below. In one embodiment, pump 83 ismodel number VPO125 as provided by Medo USA, of Cherry Hill, Ill.

[0030] Conduit 62 allows gaseous communication between console 52 andgas delivery device 56. Gas delivery device 56 may be placed within box12 and includes multiple specimen interfaces for communicatinganesthesia gas to one or more living specimens. For example, box 12typically includes a stage that supports one or more mice to be imaged,and gas delivery device 56 may be place on the stage in proximity to themice. A light-sealed hole 27 is included in a side wall of box 12 toallow a gas conduit 62 to pass therethrough while device 56 is in box12. Conduit 62 may comprise tubing or a suitable hose. For example, ⅜inch OD ¼ inch ID 90 durometer viton rubber tubing is suitable for useas conduits in FIG. 1.

[0031] An image-processing unit 26 optionally interfaces between camera20 and a computer 28 through cables 30 and 32 respectively. Computer 28,which may be of any suitable type, comprises a main unit 36 thattypically contains hardware including a processor, memory componentssuch as random-access memory (RAM) and read-only memory (ROM), and diskdrive components (e.g., hard drive, CD, floppy drive, etc.). Computer 28also includes a display 38 and input devices such as a keyboard 40 andinput mouse 42. Computer 28 is in communication with various componentsin imaging box 12 via cable 34. To provide communication and control forthese components, computer 28 includes suitable processing hardware andsoftware configured to provide output for controlling any of the devicesin imaging box 12. The processing hardware and software may include anI/O card, control logic for controlling any of the components of imagingsystem 10, and a suitable graphical user interface that facilitates userinteraction with imaging system 10. Components controlled by computer 28may include camera 20, motors responsible for camera 20 focus, motorsresponsible for position control of a platform supporting the livingspecimens, the camera lens, f-stop, etc.

[0032] Computer 28 may also include suitable processing hardware andsoftware for camera 20 such as additional imaging hardware and software,calibration software, and image processing logic for processinginformation obtained by camera 20. The logic in computer 28 may take theform of software, hardware or a combination thereof. Computer 28 alsocommunicates with a display 38 for presenting imaging information to theuser. For example, the display 38 may be a monitor, which presents animage measurement graphical user interface (GUI) that allows a user toview imaging results and also acts an interface to control the imagingsystem 10.

[0033] II. Induction Chamber

[0034] FIGS. 2A-2D illustrate induction chamber 54 of FIG. 1 inaccordance with one embodiment of the present invention. Inductionchamber 54 allows a user to anesthetize one or more living specimensthat fit within induction chamber 54 and is also commonly referred to asa ‘knockdown box’. Induction chamber 54 includes an interior cavitysized to receive living specimens and a gas inlet that allows a user tosupply an anesthesia gas to the interior cavity, as described in greaterdetail below. While induction chamber 54 will now be described as anapparatus, those skilled in the area will recognize that the presentinvention encompasses a method of using the apparatus based on thefunctional components of the induction chamber.

[0035]FIG. 2A illustrates a top prospective view of the front ofinduction chamber 54. FIG. 2B illustrates a top prospective view of theback of induction chamber 54. FIG. 2C illustrates a top prospective viewof the underside of door 124. FIG. 2D illustrates a side cross sectionalview of induction chamber 54 taken through the lateral midpoint of sidewalls 112 a and 122 d.

[0036] Referring initially to FIG. 2A, induction chamber 54 includesfour vertical side walls 122 a-d fixed to a bottom 123. Side walls 122a-d include front wall 122 a, side wall 122 b, side wall 122 c, and backwall 122 d. Side walls 122, bottom 123 and top wall 127 then comprise aset of walls that define an interior cavity 128 (FIG. 2D) withininduction chamber 54. As shown in FIG. 2D, interior cavity 128 issufficiently sized to receive multiple living specimens 134. A cavityvolume of about 2 to about 8 liters is suitable for many inductionchambers. In one embodiment, interior cavity 128 has a cavity volume ofabout 3 to about 4 liters. Interior cavity 128 may include a stage 143or platform that the living specimens rest upon.

[0037] Side walls 122, bottom 123 and top wall 127 each comprise atransparent material that allows a user to view interior chamber 128. Ina specific embodiment, lexan, a transparent plastic such aspolycarbonate, or a transparent acrylic, are used for the walls ofinduction chamber 54. Using transparent walls for induction chamber 54advantageously allows a user to view the interior of induction chamber54. Walls for induction chamber 54 may very in thickness from about ⅛inch thick to about 1 inch thick, for example.

[0038] Induction chamber 54 comprises a door or user access port thatallows user access to interior cavity 128. As shown in FIG. 2A,induction chamber 54 comprises a door 127 that comprises the top wall ofchamber 54 and spans the entire top surface area of induction chamber 54as defined by side walls 122 a-d. Door 127 is hingeably coupled to backwall 122 d using a pin 144 (FIG. 2B) that passes through a channel 141included in the hinges 125 (FIG. 2A) and a channel 142 included in door127 (FIG. 2C). Hinges 125 are screwed to the outside of back wall 122 d(FIG. 2B).

[0039] Door 127 is movable between a closed condition and various openedconditions. FIG. 2A illustrates the closed condition for door 127 andinduction chamber 54. In the closed condition as shown, door 127 restsupon the top portion of walls 122 and seals interior cavity 128 from theenvironment exterior to induction chamber 54. In one opened condition,door 127 enables user access into interior chamber to insert or removeliving specimens. In the opened conditions, door 127 enables gaseouscommunication, or gaseous flow, between interior cavity 128 and theenvironment exterior to induction chamber 54 through an opening. Thesize and profile of the opening will depend on the angle door 127 makesrelative to its closed position as shown. Thus, when door 127 isinitially opened from the position shown in FIG. 2A, a crack between thetop portion of each side wall 122 in door 127 creates an opening thatallows anesthesia gas and oxygen to flow between interior chamber 128and the environment external to induction chamber 54.

[0040] Seal 145 is disposed in a recess that runs perimetrically about atop portion of each side wall 122 (FIG. 2B). As shown in FIG. 2A, seal145 runs 360 degrees about the top opening of interior cavity 128. Seal145 is a compressible material that prevents gaseous communicationbetween interior cavity 128 and the environment exterior to inductionchamber 54 when door 127 is in the closed condition. More specifically,when door 127 is in the closed position, the bottom surface of door 127cooperates with seal 145 to prevent gaseous communication betweeninterior cavity 128 and the environment external to induction chamber54. In a specific embodiment, seal 145 comprises a rubber or silicone.

[0041] Clamp 147 is attached side wall 122 a using screws 151. Clamp 147allows a user to secure door 127 in the closed position. In addition,clamp 147 is vertically disposed such that securing clamp 147 provides acompressive force between the bottom surface of door 127 and seal 145.

[0042] Induction chamber receives low-pressure oxygen and anesthesia gasfrom console 52 and conduit 60. Induction chamber 54 thus includes atleast one gas inlet capable of providing anesthesia gas to the interiorcavity 128. As shown, induction chamber 54 includes a single gas inlet130 that supplies both anesthesia gas and oxygen from the exterior ofinduction chamber 54 to the interior cavity 128. Gas inlet 130 isdisposed in a lower portion of back wall 122 d and includes a circularport or hole through back wall 122 d that allows gaseous communicationbetween the inside and outside of induction chamber 54. As shown, gasinlet 130 includes an exterior interface 123 (FIG. 2B) that receivesconduit 60 (FIG. 1). Referring back to FIG. 1, console 52 provides amixture of oxygen and anesthesia gas to induction chamber 54. Thismixture is passed into induction chamber 54 through gas inlet 130.Console 52 includes controls that allow a user to turn on/off or varythe flowrate of oxygen and anesthesia gas provided to induction chamber54. It is understood that induction chamber 54 may include multiple gasinlets. For example, one inlet may be dedicated to anesthesia gas was asecond gas inlet is dedicated to oxygen supply.

[0043] The present invention employs an anesthesia gas to sedate livingspecimens. As the term is used herein, an anesthesia gas refers to anygas or agent that is used to induce any level of anesthetic state,unconsciousness, lack of awareness, or local or general insensibility topain for a specimen interacting with induction chamber 54. The amount ofanesthesia gas is typically determined by the control console 52 ofFIG. 1. A vaporizer included in console 52 may be used to produce theanesthesia gas and add it to low-pressure oxygen. The output of thevaporizer typically comprises a controlled and variable gas mixture oflife sustaining gases and anesthetizing gases. In a specific embodiment,isoflurane is added to low pressure oxygen by passing oxygen across avaporizer that evaporates isoflurane. In this case, the low-pressureoxygen acts as a carrier for the isoflurane, which is added to theoxygen according to the physical characteristics of isoflurane liquidand its temperature. Although the present invention is primarilydescribed with respect to using only a single anesthesia gas,isoflurane, it is understood that an anesthesia gas of the presentinvention may include multiple anesthesia gases, as one of skill in theart will appreciate.

[0044] Induction chamber 54 also comprises a gas outlet 150 capable ofdrawing anesthesia gas from interior cavity 128 when door 127 is in anopened condition. Gas outlet 150 is disposed in an upper portion of backwall 122 d and includes a circular port or hole through back wall 122 dthat allows gaseous communication between the inside and outside ofinduction chamber 54. As shown, gas outlet 150 includes an exteriorinterface 152 (FIG. 2B) that receives conduit 79, which exhausts gasesfrom induction chamber 54 to filter 81 (FIG. 1).

[0045] Gas outlet 150 actively draws and collects anesthesia gas frominterior cavity 128, and actively draws and collects anesthesia gas fromthe environment external to induction chamber 54 when door 127 is in anopened condition. To do so, gas outlet 150 is in gaseous communicationwith a negative pressure supply such as vacuum pump 83 (FIG. 1). Vacuumpump 83 provides a negative pressure to gas outlet 150 that draws gasesinto outlet 150. In one embodiment, the negative pressure is negativerelative to the pressure within interior chamber 128. In anotherembodiment, the native pressure is negative relative to the environmentexterior to induction chamber 54. This creates a draft through anyopening created by door 127 that causes air and anesthesia gas to bedrawn from the external environment, to pass in through interior cavity128, and into gas outlet 150. Thus, with suitable pressure from pump 83,anesthesia gases about to escape interior cavity 128 when door 127 opensmay be drawn and collected by gas outlet 150 before they escape. Inaddition, anesthesia gases that have escaped interior cavity 128 may bedrawn and collected by gas outlet 150 when door 127 is opened.

[0046] The flowrate of anesthesia gas and other gases through gas outlet150 may vary. In one embodiment, gas outlet 150 draws gases frominterior cavity 128 at a flowrate through gas outlet 150 greater thanthe volume of interior cavity 128 per minute. In a specific embodiment,gas outlet 150 draws gases from interior cavity 128 at a flowrate fromabout 0 L/min to about 8 L/min.

[0047] Induction chamber 54 also comprises a gas outlet obstruction 160that varies flow of anesthesia gas from interior cavity 128 through gasoutlet 150 based on the position of door 127. Typically, gas outletobstruction 160 varies flow of anesthesia gas from interior cavity 128by obstructing gas outlet 150 in some manner. Thus, gas outletobstruction 160 may plug, cap, cork, block, prevents, or otherwiseimpair gas flow through gas outlet 150.

[0048] As shown in FIG. 2D, gas outlet obstruction 160 comprises abracket 162 having a portion 162 a that rests flat against the bottomside of door 127 and is attached to door 127 using screws 164. Bracket162 also has a portion 162 b that is positioned proximate to gas outlet150 when door 127 is in the closed position. Attached to portion 162 bis screw 166, washer 168, compressible material 170 and spacer 172.Screw 166 fastens washer 168, compressible material 170 and spacer 172to portion 162 b. Compressible material 170 interfaces with gas outlet150 to seal the outlet 150 when door 127 is in the closed position.Thus, portion 162 b is proximate to gas outlet 150 such thatcompressible material 170 seals the outlet 150 when door 127 is in theclosed position. Together, portion 162 b and perimeter material of gasoutlet 150 combine to compress the compressible material 170 when door127 is in the closed condition. FIG. 2D illustrates gas outletobstruction 160 when door 127 is in the closed position. Here, gasoutlet obstruction 160 restricts flow of anesthesia gas from interiorcavity 128 through gas outlet 150. Washer 168 allows screw 166 totighten without compressing a localized portion of compressible material170. Spacer 172 allows a user to change the thickness of compressiblematerial 170 or vary the force applied between portion 162 b and theperimeter material of gas outlet 150 on compressible material 170.

[0049] In a simplified embodiment, gas outlet obstruction 160 simplycomprises a compressible material that spans the entire back side ofportion 162 b of bracket 162. Similar to the previous case, the thissimplified embodiment seals gas outlet 150 when door 127 is in theclosed condition. In addition, the gas outlet obstruction 160 allows gasto flow from interior cavity 128 through gas outlet 150 when door 127 isin an opened condition.

[0050] In one embodiment, gas outlet 150 is disposed in the top half ofa side wall 122. In this case, anesthesia gas is introduced near thebottom of induction chamber 54 and collects in interior cavity 128 whendoor 127 is closed. When door 127 opens, gas outlet 150 draws anesthesiagas from the top portion of interior cavity 128. As long as the flowratethrough gas outlet 150 is not excessive, this may result in a temporarytwo layer gaseous formation within interior cavity 128. The top layercomprises gases that move toward gas outlet 150. The bottom layercomprises anesthesia gas and oxygen supplied by gas inlet 123. Anadvantage of this design is that even with door 127 opened for shortperiods of time, living specimens is disposed near the bottom ofinduction chamber 54 may not be entirely devoid of anesthesia gas.

[0051] In one embodiment, passive gas outlet 132 is disposed in backwall 122 c. Passive gas outlet 132 passively exhausts anesthesia gasfrom interior cavity 128 based on positive pressure in interior cavity128 relative to conduit 77. Typically, this occurs when door 127 is inthe closed condition and gas outlet 150 is obstructed. In this case,continual anesthesia gas and oxygen supply into interior cavity 128builds pressure within the interior cavity and causes passive gas flowthrough gas outlet 132. Gas outlet 132 is disposed in a lower portion ofback wall 122 d and includes a circular port or hole through back wall122 d that allows gaseous communication between the inside and outsideof induction chamber 54. As shown, passive gas outlet 132 includes anexterior interface 129 (FIG. 2B) that receives conduit 77, whichexhausts gases from induction chamber 54 to filter 78 (FIG. 1).

[0052]FIG. 3 illustrates a process flow 200 for using induction chamber54 of FIG. 1 in accordance with one embodiment of the present invention.Processes in accordance with the present invention may include up toseveral additional steps not described or illustrated herein in ordernot to obscure the present invention.

[0053] In operation, a user opens door 127 (FIG. 1) and places a livingspecimen within the interior of induction chamber 54. Closing door 127seals the interior of induction chamber 54 from the ambient room via theinterface of seal 145 and door 127. In addition, a gas outletobstruction obstructs gas flow through gas outlet 150 when door 127 isin the closed condition (206). In one embodiment, the gas outletobstruction is attached to the door 127 and fully seals gas outlet 150when door 127 is in the closed condition and fully prevents gas fromflowing through gas outlet 150+.

[0054] After induction chamber 54 is sealed, oxygen and anesthesia gasare supplied to the interior via console 52 and gas inlet 130 (202). Aspressure in the interior cavity builds, exhaust gases may be passivelyremoved from induction chamber 54 via a passive exhaust included ininduction chamber 54. Gas flows into the passive exhaust based on apositive pressure accumulating inside the chamber relative to thepassive exhaust. After anesthesia delivery to the living specimen iscomplete, e.g. when the specimen has been anesthetized, door 127 may beopened to allow a lab technician to remove one or more specimens.

[0055] Opening door 127 ceases obstruction of gas outlet 150. Thiscauses anesthesia gas to be drawn through gas outlet 150 from theinterior chamber when door 127 is in the opened condition (204). In oneembodiment, the gas outlet draws gases from the interior chamber at aflow rate greater than the volume of the interior chamber per minute.This is done with a negative pressure that is applied to the gas outlet,e.g., via a pump.

[0056] When used in the imaging system 10 of FIG. 1, process flow 200may also include various additional actions related to imaging thespecimen after it has been sedated. For example, a user may remove aliving specimen from the interior cavity when the door is in the openedcondition, place the living specimen in the imaging box, and image theliving specimen, or a portion thereof, using the imaging system.

[0057] In early tests, induction chamber 54 produced improved resultsfor its intended purpose when gas outlet 150 and obstruction 160 wereused. In many cases, induction chamber 54 reduced the amount ofanesthesia gas introduced into the ambient surroundings by a factor ofabout 4-5 relative to an induction chamber without an active gas outletand gas outlet obstruction. In addition, opening door 127 did not resultin frequent living specimen arousal—for both specimens being removed andresting temporarily while another specimen was being removed.

[0058] While this invention has been described in terms of severalpreferred embodiments, there are alterations, permutations, andequivalents which fall within the scope of this invention which havebeen omitted for brevity's sake. For example, although induction chamber54 has been described with respect to an active gas outlet in a sidewall, it is understood that other designs include the gas outlet inother positions such as a top wall. It is therefore intended that thescope of the invention should be determined with reference to theappended claims.

What is claimed is:
 1. An induction chamber for delivering anesthesiagas to a living specimen, the chamber comprising: a set of wallsdefining an interior cavity; a door that is movable between an openedcondition that enables gaseous communication between the interior cavityand the environment exterior to the induction chamber through anopening, and a closed condition that seals the interior cavity from theenvironment exterior to the induction chamber; a gas inlet disposed inone of the set of walls and capable of providing anesthesia gas to theinterior cavity; a gas outlet disposed in one of the set of walls andcapable of drawing anesthesia gas from the interior cavity when the dooris in the opened condition; and a gas outlet obstruction that variesflow of anesthesia gas from the interior cavity through the gas outletbased on the position of the door.
 2. The induction chamber of claim 1wherein the gas outlet obstruction allows gas to flow from the interiorcavity through the gas outlet when the door is in the open condition. 3.The induction chamber of claim 1 wherein the gas outlet obstructionprevents flow of anesthesia gas from the interior cavity through the gasoutlet when the door is in the closed condition.
 4. The inductionchamber of claim 3 wherein the gas outlet obstruction is attached to thedoor and seals the gas outlet when the door is in the closed condition.5. The induction chamber of claim 4 wherein the gas outlet obstructioncomprises a compressible material that is compressed by interface withthe gas outlet when the door is in the closed condition.
 6. Theinduction chamber of claim 1 wherein the door comprises a top wall forthe set of walls.
 7. The induction chamber of claim 1 further comprisinga passive gas outlet disposed in one of the set of walls that passivelyexhausts anesthesia gas from the interior cavity based on positivepressure in the interior cavity when the door is in the closedcondition.
 8. The induction chamber of claim 1 wherein the gas outletdraws gases from the interior cavity at a flow rate greater than thevolume of the interior chamber per minute.
 9. The induction chamber ofclaim 7 wherein the gas outlet draws gases from the interior cavity at aflow rate from about 0 L/min to about 8 L/min.
 10. The induction chamberof claim 1 wherein the gas outlet is disposed in the top half of avertical wall of the set of walls.
 11. The induction chamber of claim 1wherein the gas outlet is in gaseous communication with a pump thatprovides negative pressure to the gas outlet.
 12. The induction chamberof claim 11 wherein the negative pressure is negative relative to theenvironment exterior to the induction chamber.
 13. The induction chamberof claim 1 further comprising a compressible seal that facilitatessealing of the interior cavity from the environment exterior to theinduction chamber when the when the door is in the closed condition. 14.The induction chamber of claim 1 the set of walls comprise a transparentmaterial that allows view of the interior chamber.
 15. A method of usingan induction chamber, the induction chamber comprising a set of wallsthat define an interior cavity and comprising a door that is movablebetween an opened condition and a closed condition, the methodcomprising: supplying an anesthesia gas into the interior cavity;drawing anesthesia gas through a gas outlet disposed on one of the setof walls when the door is in the opened condition; and obstructing gasflow through the gas outlet when the door is in the closed condition.16. The method of claim 15 wherein the gas outlet is sealed by a gasoutlet obstruction attached to the door when the door is in the closedcondition.
 17. The method of claim 15 further comprising passivelyexhausting anesthesia gas from the interior cavity based on increasedpressure in the interior cavity relative to the gas outlet when the dooris in the closed condition.
 18. The method of claim 15 wherein the gasoutlet draws gases from the interior chamber at a flow rate greater thanthe volume of the interior chamber per minute.
 19. The method of claim18 wherein the gas outlet withdraws gases from at a flow rate about 0L/min to about 8 L/min.
 20. The method of claim 15 wherein the gasoutlet is disposed in the top half of a vertical wall of the set ofwalls.
 21. The method of claim 15 further comprising applying negativepressure to the gas outlet.
 22. The method of claim 21 wherein a pumpprovides the negative pressure to the gas outlet.
 23. The method ofclaim 21 wherein the negative pressure is negative relative to theenvironment exterior to the induction chamber.
 24. The method of claim21 wherein the induction chamber is associated with an imaging systemincluding an imaging box and the method further comprises: a) removing aliving specimen from the interior cavity when the door is in the openedcondition; b) placing the living specimen in the imaging box; and c)imaging the living specimen using the imaging system.
 25. An imagingsystem for capturing an image of a living specimen with a camera, thesystem comprising: an imaging box having a set of walls enclosing aninterior cavity and a camera mount configured to position the camera toview the living specimen in the interior cavity while the livingspecimen is anesthetized; and an induction chamber comprising: a set ofwalls defining an interior cavity, a door that is movable between anopened condition that enables gaseous communication between the interiorcavity and the environment exterior to the induction chamber through anopening, and a closed condition that seals the interior cavity from theenvironment exterior to the induction chamber, a gas inlet disposed inone of the set of walls and capable of providing anesthesia gas to theinterior cavity, a gas outlet disposed in one of the set of walls andcapable of drawing anesthesia gas from the interior cavity when the dooris in the opened condition, and a gas outlet obstruction that variesflow of anesthesia gas from the interior cavity through the gas outletbased on the position of the door.